package io.github.dreamylost;

/**
编辑距离

72. Edit Distance (Hard)

Example 1:

Input: word1 = "horse", word2 = "ros"
Output: 3
Explanation:
horse -> rorse (replace 'h' with 'r')
rorse -> rose (remove 'r')
rose -> ros (remove 'e')
Example 2:

Input: word1 = "intention", word2 = "execution"
Output: 5
Explanation:
intention -> inention (remove 't')
inention -> enention (replace 'i' with 'e')
enention -> exention (replace 'n' with 'x')
exention -> exection (replace 'n' with 'c')
exection -> execution (insert 'u')
题目描述：修改一个字符串成为另一个字符串，使得修改次数最少。一次修改操作包括：插入一个字符、删除一个字符、替换一个字符。

 * @author 梦境迷离.
 * @time 2018年6月19日
 * @version v1.0
 */
public class Leetcode_72_LCS {

	/**
	 * 把word1变成word2
	 */
	public int minDistance(String word1, String word2) {
		if (word1 == null || word2 == null) {
			return 0;
		}
		int m = word1.length(), n = word2.length();
		int[][] dp = new int[m + 1][n + 1];
		for (int i = 1; i <= m; i++) {
			dp[i][0] = i;
		}
		for (int i = 1; i <= n; i++) {
			dp[0][i] = i;
		}
		for (int i = 1; i <= m; i++) {
			for (int j = 1; j <= n; j++) {
				if (word1.charAt(i - 1) == word2.charAt(j - 1)) {
					dp[i][j] = dp[i - 1][j - 1];
				} else {
					dp[i][j] = Math.min(dp[i - 1][j - 1], Math.min(dp[i][j - 1], dp[i - 1][j])) + 1;
				}
			}
		}
		return dp[m][n];
	}
}
